Method for commercial preparation of preffered isomeric forms of ester free conjugated fatty acids with solvents systems containing polyether alcohol solvents

ABSTRACT

Methods for sequential saponification and quantitative isomerization of glyceride oils containing interrupted double bond systems, with alkali in a polyether alcohol solvent to yield soaps with conjugated double bond systems are disclosed. The novel properties f the polyether alcohols allow the removal of water added with the alkali by boiling. The preferred embodiment uses a vegetable oil rich in linoleic acid such as sunflower or safflower oil, potassium hydroxide, phosph ric acid to neutralize the soaps. The reaction forms equal quantities of 9Z,11E-octadecadienoic acid and 10E,12Z-octadecadienoic acids.

BACKGROUND OF THE INVENTION AND CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is related to U.S. patent application Ser. No.09/451,710 filed Dec. 1, 1999 by Martin J. T. Reaney et al, thedisclosure of which is incorporated herein by reference.

FIELD OF INVENTION

[0002] This invention relates to an improved process for preparation ofconjugated fatty acids from materials rich in fatty acids containinginterrupted diene, triene and polyene systems. In a preferred embodimentthe reaction produces approximately equal amounts of the conjugatedlinoleic acid isomers 9Z,11E-octadecadienoic acid and10E,12Z-octadecadienoic acid from linoleic acid. The reaction is uniquein that the reaction proceeds rapidly at temperatures as low as 90° C.The process by-product stream is usable directly as a fertilizer thatlimits waste disposal costs.

[0003] Interrupted dienes moieties of fatty acids and esters thereof maybe converted to conjugated dienes, and higher polymers may also beconjugated. For examples, literature reports the synthesis of conjugatedforms of linoleic acid, linolenic acid and arachidonic acid using alkalicatalysts. Of the conjugated fatty acids that have been prepared,conjugated forms of linoleic acid are the most investigated. Conjugatedlinoleic acid or CLA is the trivial name given to a series of eighteencarbon diene fatty acids with conjugated double bonds. Applications of,and uses for, conjugated linoleic acids vary from treatment of medicalconditions such as anorexia (U.S. Pat. No. 5,430,066) and low immunity(U.S. Pat. No. 5,674,901) to applications in the field of dietetics,where CLA has been reported to reduce body fat (U.S. Pat. No. 5,554,646)and to inclusion in cosmetic formulae (U.S. Pat. No. 4,393,043).

[0004] Conjugated fatty acids, specifically CLA shows similar activityin veterinary applications. In addition, CLA has proven effective inreducing valgus and varus deformity in poultry (U.S. Pat. No.5,760,083), and attenuating allergic responses (U.S. Pat. No.5,585,400). CLA has also been reported to increase feed conversionefficiency in animals (U.S. Pat. No. 5,428,072). CLA-containing bait canreduce the fertility of scavenger bird species such as crows and magpies(U.S. Pat. No. 5,504,114).

[0005] Industrial applications for conjugated fatty acids also existwhere they may be used as lubricant constituents (U.S. Pat. No.4,376,711). Conjugation can be used as a means to chemically modifyfatty acids, such as linoleic acid, so that they are readily reactive toDiels-Alder reagents (U.S. Pat. No. 5,053,534). In one method linoleicacid was separated from oleic acid by first conjugation then reactionwith maleic anhydride followed by distillation (U.S. Pat. No.5,194,640).

[0006] Conjugated fatty acids occur naturally in ruminant depot fats.The predominant form of conjugated fatty acid in ruminant fat is the9Z,11E-octadecadienoic acid which is synthesized from linoleic acid inthe rumen by micro-organisms like Butryvibrio fibrisolvens. The level ofCLA found in ruminant fat is in part a function of dietary9Z,12Z-octadecadienoic acid and the level of CLA in ruminant milk anddepot fat may be increased marginally by feeding linoleic acid (U.S.Pat. No. 5,770,247).

[0007] Conjugated fatty acids may also be prepared by any of severalanalytical and preparative methods. Pariza and Ha pasteurized a mixtureof butter oil and whey protein at 85° C. for 5 minutes and notedelevated levels of CLA in the oil (U.S. Pat. No. 5,070,104). CLAproduced by this mechanism is predominantly a mixture of9Z,11E-octadecadienoic acid and 10E,12Z-octadecadienoic acid.

[0008] Conjugated fatty acids have also been produced by the reaction ofsoaps with strong alkali bases in molten soaps, alcohol, and ethyleneglycol monomethyl ether (U.S. Pat. Nos. 2,389,260; 2,242,230 &2,343,644). These reactions are inefficient, as they require themultiple steps of formation of the fatty acid followed by production ofsoap from the fatty acids, and subsequently increasing the temperatureto isomerize the linoleic soap. The conjugated fatty acid product isgenerated by acidification with a strong acid (sulfuric or hydrochloricacid) and repeatedly washing the product with brine or CaCl₂. Iwata etal. (U.S. Pat. No. 5,986,116) overcame the need for an intermediate stepof preparation of fatty acids by reacting oils directly with alkalicatalyst in a solvent of propylene glycol under low water or anhydrousconditions. Reaney et al., in U.S. patent application Ser. No.09/451/710, entitled “Commercial production of CLA”, and Yurawecz,Mossaba, Kramer, Pariza and Nelson Eds. Advances in conjugated linoleicacid research, Vol. 1 pp.39-54 identified that conjugated fatty acidproducts prepared in the presence of glycol and other alcohols maytransesterify with fatty esters and produce esters of the glycol. Suchesters have been identified by Reaney et al. (unpublished data) incommercial products and in CLA prepared in propylene glycol by themethod of U.S. Pat. No. 5,986,116. Esters of CLA containing fatty acidsand propylene glycol have biological activity and therefore theirpresence in the CLA product is undesirable.

[0009] Conjugated fatty acids have been synthesized from fatty acidsusing SO₂ in the presence of a sub-stoichiometric amount of soap formingbase (U.S. Pat. No. 4,381,264). The reaction of linoleic acid with thiscatalyst produced predominantly the all trans configuration of CLA.

[0010] Efficient synthesis of 9Z,11E-octadecadienoic from ricinoleicacid has been achieved (Russian Patent 2,021,252). This synthesis,although efficient, uses expensive elimination reagents such as1,8-diazobicyclo-(5,4,0)-undecene. For most applications the cost of theelimination reagent increases the production cost beyond the level atwhich commercial production of CLA is economically viable.

[0011] Of these methods, alkali isomerization of soaps is the leastexpensive process for bulk preparation of conjugated fatty acids.However, the use of either monohydric or polyhydric alcohols in alkaliisomerization of conjugated fatty acids can be problematic. Loweralcohols are readily removed from the conjugated product but theyrequire the production facility be built to support the use of flammablesolvents. Higher molecular weight alcohols and polyhydric alcohols areconsiderably more difficult to remove from the product and residuallevels of these alcohols (e.g. ethylene glycol) may not be acceptable inthe conjugated product.

[0012] Water may be used in place of alcohols in the conjugation offatty acids by alkali isomerization of soaps (U.S. Pat. Nos. 2,350,583and 4,164,505). When water is used for this reaction it is necessary toperform the reaction in a pressure vessel whether in a batch (U.S. Pat.No. 2,350,583) or continuous mode of operation (U.S. Pat. No.4,164,505). The process for synthesis of conjugated fatty acids fromsoaps dissolved in water still requires a complex series of reactionsteps. Bradley and Richardson (Industrial and Engineering ChemistryFebruary 1942 vol. 34 no.2 237-242) were able to produce conjugatedfatty acids directly from soybean triglycerides by mixing sodiumhydroxide, water and oil in a pressure vessel. Their method eliminatedthe need to synthesize fatty acids and then form soaps prior to theisomerization reaction. However, they reported that they were able toproduce oil with up to 40 percent CLA. Quantitative conversion of thelinoleic acid in soybean oil to CLA would have produced a fatty acidmixture with approximately 54 percent CLA.

[0013] Commercial conjugated linoleic acid often contains a mixture ofpositional isomers that may include 8E,10Z-octadecadienoic acid,9Z,11E-octadecadienoic acid, 10E,12Z-octadecadienoic acid, and11Z,13E-octadecadienoic acid (Christie, W. W., G. Dobson, and F. D.Gunstone, (1997) Isomers in commercial samples of conjugated linoleicacid. J. Am. Oil Chem. Soc. 74,11,1231).

[0014] The present invention describes a method of production ofconjugated fatty acids using a polyether alcohol, such as polyethyleneglycol alone or with a co-solvent as a reaction medium and vegetableoil, a fatty acid or ester thereof containing one or more interrupteddiene moieties. In a preferred embodiment the reaction products oflinoleic acid in polyether glycol containing solvent are primarily9Z,11E-octadecadienoic acid and 10E,12Z-octadecadienoic acid in equalamounts. The reaction product is readily released by acidification.

SUMMARY OF THE INVENTION

[0015] In the present invention the quantitative production ofconjugated fatty acids from fatty acids and esters containinginterrupted dienes or higher polymers is achieved by heating the oil ina polyether alcohol with an alkali base. As it is normal for smallamounts of water to be present in the reaction materials this water mayeither be boiled from the reaction mixture by addition of heat orreaction must be performed in a pressurized vessel; thereafter, thereaction mixture is neutralized by a strong acid, with solutions ofH3PO4 being preferred. Surprisingly. when polyethylene glycol (PEG), andother polyether alcohols, are used as a solvent, the boiling reactionmixture does not foam uncontrollably. Surprisingly, the PEG solventallows the reaction to proceed rapidly at temperatures as low as 90° C.The selection of H₃PO₄ as the acid and KOH as the base allow theresultant salt solution to be disposed of in surface applications as aliquid or solid fertilizer. The reaction minimizes the production ofundesirable isomers.

[0016] Thus, by one aspect of the invention there is provided a processfor producing a preferred isomeric mix of a conjugated linoleicacid-rich fatty acid mixture comprising reacting a linoleic acid-richoil with a base in the presence of a catalytic amount of said base, in apolyether alcohol solvent containing medium, at a temperature above 90°C., and separating said conjugated linoleic acid-rich fatty acid mixturefrom said solvent by the addition of acid. In a preferred embodiment,300 MW polyethylene glycol is the preferred polyether alcohol.

BRIEF DESCRIPTION OF DRAWINGS

[0017]FIG. 1 is the gas liquid chromatogram of CLA prepared in water at210° C. for 4 h;

[0018]FIG. 2 is the gas liquid chromatogram of CLA prepared in PEG at130° C. for 4 h;

[0019]FIG. 3 is the gas liquid chromatogram of conjugated fatty acidsprepared by treating flax oil in PEG at 130° C. for 4 h; and

[0020]FIG. 4 is the 1H nuclear magnetic resonance spectrum of theconjugated fatty acids prepared by treating flax oil and KOH in PEG at130° C. for 4 h;

DETAILED DESCRIPTION OF THE INVENTION

[0021] The disclosed process quantitatively converts interrupted dienemoieties or higher interrupted polymers occurring in vegetable oils,fatty acid and esters of fatty acids to conjugated dienes or polymerswith conjugated double bond moieties respectively. The process involvesblending said fatty acid or ester thereof with 1-6 moles of base, partof which acts as a reactant and part of which acts as a catalyst,dissolved in a polyether alcohol and 1 to 100 moles of water per mole ofhydrolysable acyl groups. The vegetable oil, fatty acids and esters mayinclude cottonseed, cucumber, grape seed, corn, safflower, soybean,sunflower or walnut oil or any other oil, wax or ester that is rich ininterrupted diene moieties or borage oil, flax oil or any other oil, waxor ester that is rich in interrupted polyene moieties. The reaction willproceed if about 1 mole of a base such as sodium metal, sodiumhydroxide, sodium alkoxylate, sodium carbonate, sodium bicarbonate,potassium metal, potassium hydroxide, potassium carbonate, potassiumbicarbonate or potassium alkoxylate is used as reactant and up to 5moles are used as the catalyst. The least expensive alkali that does notrepresent a disposal problem is potassium hydroxide. Furthermore,metallic alkali produces explosive hydrogen gas when added to water andmetal alkoxylates are flammable. These factors support the use ofpotassium hydroxide as the preferred catalyst/reactant. The reactionproceeds at temperatures above 90° C. and accelerates with increases intemperature. The comparatively low reaction temperature achieved inpolyethylene glycol is surprising as the reaction in a solventcontaining ethylene glycol, the parent molecule, is 20 fold slower underthe same conditions. We have found that the polyether alcohols aresuperior solvents to glycols. It is surprising that the conversion ofvegetable oil to CLA may be performed in as little as 1 part ofpolyether alcohol solvent per 2 parts of interrupted fatty acid or esterthereof. Preferred embodiments involve performing the reaction above130° C. It is a unique characteristic of this reaction that water in thereaction boils easily without foaming and it is not necessary to confinethe reaction in a sealed pressure vessel.

[0022] The reaction proceeds very rapidly at temperatures above 130° C.and is sensitive to small changes in temperature. The reaction vesselused for the process must have a homogeneous temperature or the reactionwill not proceed uniformly. Homogeneous temperature is achieved bystirring or turbulent flow conditions. In a preferred embodiment thereaction mixture is prepared with a sub-stoichiometric level of KOH andheated to the reaction temperature. The reactor is then charged withadditional catalyst to begin the reaction. Using this method thereaction starts in the time required adding the catalyst. The reactionis terminated either through addition of acid or through the rapidcooling of the reaction mixture to prevent the further formation ofpositional isomers.

[0023] After the reaction is complete the mixture is cooled to 90-100°C. for separation of the reaction by-products. Acid is added to thereaction mixture to hydrolyze the soaps in the reactor. It is preferredto bring the pH of the contents of the reactor to pH 4 or less throughthe addition of either a mineral or organic acid. Acids that may be usedinclude, but are not limited to, hydrochloric acid, sulfuric acid,phosphoric acid, carbonic and citric acid. it is found that the use ofsulfuric and hydrochloric acid is problematic in that these strong acidsmay react chemically with the conjugated fatty acid during separation.The preferred embodiment of this invention involves the use ofphosphoric acid or citric acid to hydrolyze the soaps. When phosphoricacid is used the waste solution can be neutralized and used as a surfaceapplied fertilizer and there are no disposal costs for discarding thisproduct.

[0024] Poly ethers have some solubility in the fatty acid phase. We havefound that polyethylene glycol 300 (PEG) accumulated to a concentrationof between 1 and 7 percent in the fatty acid phase during separation.This relatively high concentration of polyether alcohol could not beeffectively removed from the fatty acids by water washing or washingwith brine. However, we have discovered that the polyether alcohol couldbe removed from the fatty acid layer by washing the fatty acids with 70percent aqueous phosphoric acid at between 85 and 110° C. We found thatthe emulsion breaking properties and phase partitioning properties ofpolyether alcohol molecules of widely different molecular sizes (PEG 300and PEG 8,000, having molecular weights of 300 g/mole and 8000 g/molerespectively) to be similar.

[0025] Reaction progress was determined by gas liquid chromatography.FIG. 1 is the chromatogram of the product of reaction of sunflower withKOH in water and FIG. 2 is a chromatogram of the reaction of sunfloweroil with KOH in PEG. As may be concluded from FIGS. 1 and 2, thereaction in water produces different isomers than the reaction in PEG.The reaction in PEG produces primarily the preferred9Z,11E-octadecadienoic acid and 10E,12Z-octadecadienoic acid isomericmixture.

[0026] From examination of FIG. 3 it is apparent that the signalnormally associated with the methylene group between the two olefinicgroups that should occur near 2.6 ppm is absent. It is also apparentthat signals associated with conjugated diene systems in the 5.3 to 6.3ppm region are now present. The absence of one signal with theconcomitant appearance of the other signal is evidence that conjugationhas been achieved. FIG. 4 indicates that there are the two expectedpeaks associated with conjugated linoleic acid, similar to FIG. 2, and amajor apparent single peak at 28.3 minutes representing the conjugatedlinolenic acids.

EXAMPLES Example 1

[0027] Sequential Hydrolysis and Isomerization of One Part Safflower Oilto CLA in One Part PEG 300.

[0028] To 600 g of PEG 300 were added commercial safflower oil (590 g)and aqueous KOH (45% w/w, 299 mL). The resulting reaction mixture washeated at 140° C. for 2 hours in a two litre beaker with vigorousagitation. During heating vigorous boiling occurred, as water was lostfrom the system. After cooling to 100° C., the reaction mixture wasacidified with H₃PO₄ (85%, 222 ml).

[0029] The resulting mixture was heated for 0.5 h at 95° C. Afterstanding for 0.5 hours at 95° C., the top CLA layer was removed, washedwith H₃PO₄ (60%, 222 mL) at 95° C. for 30 minutes to remove excess PEGand water. The dried CLA layer was removed. The CLA product containedless than 0.1% water and less than 0.0125% PEG as determined by themethod of Muir et al. (Muir, A., A. Aubin and M. J. T. Reaney 1998,“Determination of polyethylene glycol (PEG 300) in long chain free fattyacid mixtures by reverse phase high performance liquid chromatography”,Journal of Chromatography A 810:241-244). The quantitative conversion oflinoleic acid to CLA was confirmed by gas chromatography as describedabove. Under these reaction conditions most of the linoleic acid hadreacted to form conjugated linoleic acids. Of the 74.2% linoleic acid inthe starting material a total of 6.2% remained unreacted in the finalproduct. Complete conversion of linoleic acid was achieved by longerreaction times not shown here. TABLE 1 Fatty acid composition of CLAcontaining lipids derived from safflower oil. Fatty acid Ex 1 Ex 2 Ex 3Ex 4 Ex 5 Ex 6 Palmitic acid 7.66 7.21 7.41 7.32 7.15 7.57 Stearic Acid2.43 2.40 2.41 2.40 2.32 2.36 Oleic acid 16.01 15.75 15.73 15.70 15.2615.94 Linoleic acid 6.17 13.04 2.27 4.00 65.54 3.48 9Z,11E-octa- 31.4128.30 33.73 32.52 4.12 31.83 decadienoic acid 10E,12Z-octa- 32.21 30.4735.10 34.41 4.24 35.21 decadienoic acid 9E,11E-octa- 1.88 1.73 1.95 2.04<0.5 2.13 decadienoic acid 10E,12E-octa- 1.52 1.08 1.39 1.60 <0.5 1.44decadienoic acid Ex 7 Ex 8 Ex 11 Ex 12 Palmitic acid 7.41 7.54 7.21 7.02Stearic Acid 2.36 2.49 2.59 2.57 Oleic acid 15.65 16.27 8.61 8.89Linoleic acid 33.70 1.76 7.38 1.49 9Z,11E-octa- 18.82 33.02 33.78 37.42decadienoic acid 10E,12Z-octa- 19.56 34.46 36.84 39.21 decadienoic acid9E,11E-octa- 1.34 2.09 2.37 2.11 decadienoic acid 10E,12E-octa- 1.132.36 1.21 1.26 decadienoic acid

Example 2

[0030] Sequential Hydrolysis and Isomerization of Two Parts SafflowerOil to CLA in One Part of PEG 300.

[0031] All conditions were similar to example 1 except that 300 g of PEG300 were added commercial safflower oil (590 g) and aqueous KOH (45%w/w, 299 mL). The conversion of linoleic acid to CLA was confirmed bygas chromatography as described above. Under these reaction conditionsmost of the linoleic acid had reacted to form conjugated linoleic acids.Of the 74.2% linoleic acid in the starting material a total of 13.0%remained unreacted in the final product. Complete conversion of linoleicacid was achieved by longer reaction times not shown here

Example 3

[0032] Sequential Hydrolysis and Isomerization of Safflower Oil to CLAin PEG 200.

[0033] All conditions were similar to example 1 except that PEG 200(molecular weight 200 g/mole) was substituted for PEG 300. Theconversion of linoleic acid to CLA was confirmed by gas chromatographyas described above. Under these reaction conditions most of the linoleicacid had reacted to form conjugated linoleic acids. Of the 74.2%linoleic acid in the starting material a total of 2.3% remainedunreacted in the final product. Conversion of linoleic acid of linoleicacid to CLA could be considered to be complete for commercial purposes.

Example 4

[0034] Sequential Hydrolysis and Isomerization of Safflower Oil to CLAin PEG 600.

[0035] All conditions were similar to example 1 except that PEG 600 wassubstituted for PEG 300. The conversion of linoleic acid to CLA wasconfirmed by gas chromatography as described above. Under these reactionconditions most of the linoleic acid had reacted to form conjugatedlinoleic acids. Of the 74.2% linoleic acid in the starting material atotal of 4.0% remained unreacted in the final product. Completeconversion of linoleic acid was achieved by longer reaction times notshown here

Example 5

[0036] Sequential Hydrolysis and Isomerization of Safflower Oil to CLAin Propylene Glycol.

[0037] All conditions were similar to example 1 except that propyleneglycol was substituted for PEG 300. The conversion of linoleic acid toCLA was confirmed by gas chromatography, as described above. Under thesereaction conditions very little of the linoleic acid had reacted to formconjugated linoleic acids. Of the 74.2% linoleic acid in the startingmaterial a total of 65.5% remained unreacted in the final product. Thisresult shows that propylene glycol is an inferior reaction solvent topolyether alcohols.

Example 6

[0038] Sequential Hydrolysis and Isomerization of Safflower oil to CLAin PEG 300 in a Sealed Pressure Reactor.

[0039] To 300 g of PEG 300 were added commercial safflower oil (295 g)and aqueous KOH (45% w/w, 149.5 mL). The resulting reaction mixture washeated at 180° C. for 4 hours in a sealed high pressure reactor withvigorous agitation. During heating boiling could not occur as thereactor was sealed throughout the reaction. After cooling to 100° C.,the reaction mixture was removed and placed in a 2000 mL beaker andacidified with H₃PO₄ (60%, 222 ml). The resulting mixture was heated for0.5 h at 95° C. After standing for 0.5 hours at 95° C., the top CLAlayer was removed, washed with H₃PO₄ (60%, 222 mL) at 95° C. for 30minutes to remove excess PEG and water. The dried CLA layer was removed.The CLA product contained less than 0.1% water and less than 0.0125% PEGas determined by the method of Muir et al., 1998. The quantitativeconversion of linoleic acid to CLA was confirmed by gas chromatographyas described above.

Example 7

[0040] Sequential Hydrolysis and Isomerization of Safflower Oil to CLAin a Mixture of PEG 300 and Propylene Glycol.

[0041] All conditions were similar to example 1 except that a mixture ofpropylene glycol and PEG 300 (1:1, w:w) was substituted for PEG 300alone. The conversion of over half of the linoleic acid to CLA wasconfirmed by gas chromatography as described above. Of the 74.2%linoleic acid in the starting material a total of 31.8% remainedunreacted in the final product. Comparison of this result to example 5shows that PEG 300 can readily accelerate the conversion of linoleicacid to CLA in other solvents.

Example 8

[0042] Refining CLA Enriched Fatty Acids

[0043] The fatty acids produced by all of the methods mentioned abovehave a straw yellow colour and contain some metal ions as determined byinductively coupled plasma spectrometry. The yellow colour detracts frommarketability and the metal ions may cause the material to be unstable.One thousand grams of fatty acid produced as described in example 1 washeated under vacuum in an agitated sealed vessel at 70° C. and 10 gramsof bleaching clay (Supreme 120 FF), was added. The mixture wascontinuously stirred and heated to 105° C., under vacuum, for 30minutes. When the temperature of the mixture had decreased to 60° C.,the vacuum was released. The mixture was then filtered through a Celitefilter bed. The refining treatment had no effect on the fatty acidcomposition of the CLA containing product but improved the colour to alighter yellow.

Example 9

[0044] Removal of PEG from CLA by Washing with Phosphoric Acid.

[0045] Polyethylene glycol 300 (5 g) was dissolved in 100 grams of CLArich oil produced as described in example 1 and the sample was heatedand stirred in 50 mL water at 100° C. for 15 min. The PEG 300 content ofupper CLA phase was determined by the method of Muir et al. 1998(supra). It was found that substantial amounts of PEG were detectable inthe CLA phase. The experiment was repeated in a similar manner exceptthat the water was replaced with 50 mL of phosphoric acid and themixture was stirred at 110° C. for 15 min. After the latter treatmentPEG was not detected in the upper CLA rich phase.

Example 10

[0046] Production of CLA in PEG 300 in a Continuous Reactor.

[0047] To 300 g of PEG 300 were added commercial safflower oil (295 g)and solid KOH (74 g). The resulting reaction mixture was heated at 120°C. for 20 minutes in a one-litre beaker with vigorous agitation. Duringheating boiling occurred, as a small amount of water was lost from thesystem. After cooling to 60° C., the reaction mixture was pumped througha heated tubular reactor. The reaction temperature was adjusted toeither 170° C. or 180° C. and the rate of pumping was adjusted so thatthe reaction time was between 5 and 15 minutes. The conversion oflinoleic acid to CLA was confirmed by gas chromatography as describedabove (results shown in table 2). Under these reaction conditions longerretention times and higher temperatures increased the total conversion.One skilled in the art of reactor design could develop a reactor tocontinuously convert linoleic acid dissolved in alkali solutions toconjugated linoleic acid. TABLE 2 Flow Rate (Temp° C.) 1.5 1.0 0.5 1.51.0 0.5 Fatty Acids (170) (170) (170) (180) (180) (180) Palmitic Acid6.74 6.73 6.81 7.06 6.93 6.76 Stearic Acid 2.48 2.47 2.49 2.49 2.51 2.50Oleic Acid 8.13 8.17 8.30 8.29 8.28 8.30 Linoleic Acid 76.24 68.77 61.0369.79 60.21 43.94 9Z,11E-octa- 3.11 6.41 9.97 6.02 10.26 17.42decadienoic acid 10E,12Z-octa- 3,29 6.48 10.62 6.35 10.94 18.90decadienoic acid 9E,11E-octa- <0.5 0.60 0.77 <0.5 0.87 1.51 decadienoicacid 10E,12E-octa- <0.5 <0.5 <0.5 <0.5 <0.5 0.68 decadienoic acid

Example 11

[0048] Sequential Hydrolysis and Isomerization of Safflower Oil to CLAin Isopropyl-idene-rac-Glycerol.

[0049] All conditions were similar to example 1 except that1,2-O-isopropyl-idene-rac-glycerol (a diether alcohol with a chemicalstructure that is very different from polyethylene glycol) wassubstituted for PEG 300 and the reaction temperature was elevated to150° C. The quantitative conversion of linoleic acid to CLA wasconfirmed by gas chromatography as described above.

Example 12

[0050] Production of CLA Using a Linoleic Acid Source >80%

[0051] All conditions were similar to example 1 except that a >80%linoleic acid source was substituted for safflower oil. The quantitativeconversion of linoleic acid to CLA was confirmed by gas chromatographyas described above.

Example 13

[0052] Commercial Scale Conversion of Safflower Oil to CLA in PEG 300

[0053] To 340 kg of PEG 300 was added solid KOH (80 kg). The resultingmixture was heated at 130° C. for 2 hours in 1000 litre reaction vesselwith vigorous agitation. To the heated PEG was added commercialsafflower oil (335 kg) and the temperature was raised and maintain at140° C. for 4 hours with vigorous agitation. After cooling to 110° C.,the reaction mixture was acidified with H₃PO₄ (75%, 220 kg). Theresulting mixture was agitated for 0.5 h at 110° C. After standing for0.1 hours at 110° C., the bottom layer containing salts, glycerol, PEG,excess H₃PO₄ and other non-free fatty acid materials was removed. TheCLA layer was washed with H₃PO₄ (75%, 110 kg) and the CLA layer wasseparated. The acid washing step was repeated one more time. The CLA wasfinally vacuumed dried and filtered. The quantitative conversion oflinoleic acid to CLA was confirmed by gas chromatography as describedabove.

Example 14

[0054] Commercial Scale Conversion of Sunflower Free Fatty Acids to CLAin PEG 300

[0055] To 340 kg of PEG 300 was added solid KOH (80 kg). The resultingmixture was heated at 130° C. for 2 hours in 1000 litre reaction vesselwith vigorous agitation. To the heated PEG was added sunflower freefatty acid (335 kg) and the temperature was raised and maintain at 130°C. for 4 hours with vigorous agitation. After cooling to 105° C., thereaction mixture was acidified with H₃PO₄ (75%, 220 kg). The resultingmixture was agitated for 0.5 h at 110° C. After standing for 0.1 hoursat 110° C. the top CLA layer was removed, washed with H₃PO₄ (75%, 110kg) at 105° C. for 30 minutes to remove excess PEG and water. Thewashing step was repeated one more time. The CLA was finally vacuumeddried and filtered. The quantitative conversion of linoleic acid to CLAwas confirmed by gas chromatography as described above.

Example 15

[0056] Sequential Hydrolysis and Isomerization Flax Oil to ConjugatedTriene Fatty Acids in PEG 300.

[0057] To 600 g of PEG 300 were added commercial flax oil (590 g) andsolid KOH (150 g). The resulting reaction mixture was heated at 130° C.for 4 hours in a 2 litre beaker with vigorous agitation After cooling to100° C., a 5 ml aliquot of the reaction mixture was removed, acidifiedwith excess H₃PO₄ (75%, 20 ml) and stirred at 100° C. for 15 minutes.The layers were allowed to separate and a sample of the top layer wasremoved for analysis. FIG. 3 shows the gas chromatographic profile ofthe isomerized product. FIG. 4 show the 1H nuclear magnetic resonancespectrum of the conjugated fatty acids prepared by heating flax oil andKOH in PEG at 130° C. for 4 h.

What is claimed is:
 1. A process for producing a conjugated fattyacid-rich mixture comprising: reacting a fatty acid rich oil thatcontains some fatty acids with moieties selected from interrupted diene,triene and polyene with a stoichiometric amount of a base so as toconvert acids and esters to soaps, in the presence of a catalytic amountof said base, in an medium containing a polyether alcohol solvent at atemperature above 90° C., and separating said conjugated fatty acid-richfatty acid mixture from said polyether alcohol solvent by the additionof acid.
 2. A process as claimed in claim 1 wherein said medium alsocontains a co-solvent.
 3. A process as claimed in claim 1, wherein saidoil is a vegetable oil selected from the group consisting of cottonseed,cucumber, grapeseed, corn, safflower, soybean, sunflower, flax seed,borage and walnut oil.
 4. A process as claimed in claim 1, wherein saidbase is selected from the group consisting of sodium metal, sodiumhydroxide, sodium alkoxylate, sodium bicarbonate, sodium carbonate,potassium metal, potassium hydroxide, potassium bicarbonate, potassiumcarbonate and potassium alkoxylate.
 5. A process as claimed in claim 1including the step of cooling said reaction mixture to a temperature ofbetween about 90° and about 100° before said separating step.
 6. Aprocess as claimed in claim 1 wherein pH of said cooled reaction mixtureis reduced to less than pH
 4. 7. A process as claimed in claim 1,wherein said acid is selected from the group consisting of hydrochloric,sulfuric, phosphoric and citric acid.
 8. A process as claimed in claim 1wherein said temperature is in the range 130°-180° C.
 9. A process asclaimed in claim 1 wherein said temperature is about 140° C.
 10. Aprocess, as claimed in claim 1, wherein the polyether alcohol solvent ispolyethylene glycol with a molecular weight of at least 200 g/mole. 11.A process as claimed in claim 1, wherein at least 85% of said conjugatedfatty acid produced comprises 9Z,11E-octadecadienoic acid and10E,12Z-octadecadienoic acid.
 12. A process as claimed in claim 1,wherein the reaction produces similar amounts of 10E,12Z-octadecadienoicacid and 9Z,11E-octadecadienoic acid.
 13. A process as claimed in claim2, wherein the polyether alcohol includes water as a cosolvent.
 14. Aprocess as claimed in claim 2, wherein the polyether alcohol includes analcohol as a cosolvent.
 15. A process as claimed in claim 2, wherein thepolyether alcohol includes propylene glycol as a cosolvent.
 16. Aprocess as claimed in claim 2, wherein the polyether alcohol includesglycerol as a cosolvent.
 17. A process as claimed in claim 1, whereinthe process is a continuous reaction.